[Wien] Are there difference between the cohesive energy and chemical potential?

[L.Z. Sun]

Yes, there are.The cohesive (lattice) energy is the energy that must be
added to the crystal to separate its component neutral atoms (ions) into
neutral free atoms (ions) at rest at infinite separation.
Chemical potential is defined as mu=G/N, where G=U-TS+PV, and N is the total
number of particles. At zero temperature (T=0) and constant volume (V=cte),
one can conclude that mu=U/N, where U as internal energy at such
circumstances is the total energy which can be calculated by wien2k code,
and N is the number of electrons. So obviously in the case of
mu=U/N,chemical potential should be equal to Fermi energy, that is mu=E_f.


Does this mean that the chemical potential alway be negative? so does the Fermi energy?
and i remember the defination of the chemical potential is :
mu=d(G)/d(N)
can this defination be treated as mu=U/N?so do in the WIEN2K?


Now I think it is clear that cohesive (lattice) energy refers to the number
of atoms (ions), but chemical potential refers to the number of electrons.


>>  Hi,all wien2k users:
>>     I have a basic physical question. Are there difference between the
cohesive energy and chemical potential?
>> 
>>      Regards
>> 
>> 
>> 
>> 

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